Medicine dispensing device

ABSTRACT

Some embodiments of a wearable, disposable medicine dispensing device may include a piston rod that is advanced to dispense medicine from the device. A rotational motor may be coupled to a drive mechanism so as to carry out a certain number of revolutions and thereby displace the piston rod by a desired distance. Such a device can be used in a method of dispensing liquid medicine.

This application is a national stage application under 35 U.S.C. §371that claims the benefit of PCT/DK2006/000195 filed on Apr. 6, 2006 andentitled “An Actuator,” which claims priority to the following Denmarkpatent applications: serial no. PA 2005 00483 filed on Apr. 6, 2005,serial no. PA 2005 005423 filed on Apr. 14, 2005, and serial no. PA 200500817 filed on Jun. 3, 2005. The entire contents of these priorapplications are incorporated herein by reference.

The present invention relates to a method of dispensing liquid medicinecomprising the steps of providing a wearable, disposable dispensingdevice comprising a syringe having a cylinder and a plunger displaceablein said syringe cylinder for pressing medicine out of said syringecylinder and a drive mechanism connected to said plunger for displacingsaid plunger in said cylinder, and an electrical motor connected to abattery and to said drive mechanism for providing a rotary force to saiddriving mechanism for displacing said plunger, displacing said plunger acertain distance in connection with a cycle of said driving mechanism.

Methods of this type are known, wherein the electrical motor iscontrolled by a control means so as to carry out a certain number ofrevolutions for each cycle corresponding to the desired distance ofdisplacement of the plunger.

In connection with such methods it is important that no more than thepredetermined amount of medicine be dispensed per cycle as otherwiselife threatening dosages may be dispensed.

When utilizing an electrical motor, a short circuit can entail that themotor does not stop after the predetermined number of revolutions orthat the motor starts by itself.

Security means have been suggested to ensure that the predetermineddosage is not exceeded, for instance monitoring the amount of liquiddispensed per cycle or monitoring the displacement distance of theplunger or the amount of revolutions of the motor per cycle withinterruption means being activated if the monitored elements exceed acertain value.

There exists a need for a simple and fail-safe method to avoidover-dosage of medicine. One main object of the invention is to meetthis need.

According to the invention this object is achieved by the cyclecomprising rotating said electrical motor in a first direction ofrotation and subsequently rotating said electrical motor in the oppositedirection of rotation.

Hereby, any short-circuit of the motor will not entail continuedrotation of the motor in one direction with ensuing continued dispensingof medicine.

The invention furthermore relates to a wearable, disposable medicinedispensing device comprising:

-   -   a syringe having cylinder and a plunger displaceable in the        syringe cylinder for pressing medicine out of said syringe        cylinder,    -   a drive mechanism connected to said plunger for displacing said        plunger in said cylinder, and    -   an electrical motor connected to a battery and to said drive        mechanism for providing a rotary force to said driving mechanism        for displacing said plunger, and    -   control means adapted for repeatedly reversing the direction of        rotation of said electrical motor.

In a further aspect, the present invention relates to an actuatorcomprising:

-   -   a rotational motor.    -   one or more elongate, flexible elements such as a string, a        filament, a strip, a ribbon and combinations thereof, said one        or more elements being attached to said motor for rotation        thereby and to a displaceable body,        such that rotation of said motor twists said one or more        elements and shortens the overall length thereof so that said        displaceable body is displaced by the shortened element or        elements.

Such an actuator according to the invention may be used in connectionwith medicine dispensing devices, but also in any application where arotational force or movement is to be utilized to displace a body.

DESCRIPTION OF DRAWINGS

In the following the invention will be described more in detail inconnection with two embodiments shown, solely by way of example, in theaccompanying drawings, where

FIG. 1 shows a first embodiment of a device according to the inventionseen in perspective and with the top part of the housing removed,

FIG. 2 shows a perspective view of the drive mechanism of the deviceaccording to the invention in FIG. 1,

FIG. 3 is an exploded View of some of the drive mechanism elements ofthe device in FIG. 1, and

FIGS. 4 and 5 are views corresponding to FIG. 2 with the drive mechanismin other positions, and

FIGS. 6-9 are views of a second embodiment of the device according tothe invention corresponding to FIGS. 1, 2, 4 and 5, respectively.

FIGS. 10-14 show a perspective view of a third embodiment of the deviceaccording to the invention in different sequential states during a firsthalf cycle during rotation of the electrical motor in a first directionof rotation,

FIGS. 15 a, b and c are views of some of the drive mechanism elements ofthe device in FIGS. 10-14 in different states during the cycle.

FIG. 16 is a schematic perspective view of a first embodiment of anactuator according to the invention, and

FIGS. 17 a-b very schematically show a second embodiment of an actuatoraccording to the invention at two different phases of an actuationcycle.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring now to FIGS. 1-5, a wearable disposable dispensing device formedicine referred to generally by the numeral 1 and of the typedescribed in WO 2004/041330 and WO 2004/056412, the disclosure of whichis hereby incorporated herein by reference, comprises a housing 2, whereonly the bottom half is shown for the sake of clarity, a cylindricalmedicine container or carpule 3 having at one end a silicone body forreceiving a catheter for dispensing medicine from the interior of thecarpule to a human body and being open at the opposite end to receive aflexible piston rod 5 for displacing an internal not shown plunger orpiston in the carpule 3 for forcing medicine out through a catheterneedle assembly connected to the silicone body 4.

The flexible piston 5 is composed of segments hinged together andoutwardly threaded guided by a rail 6 received in recesses in each ofthe segments of the rod 5. The not shown outward threads of the segmentsof the flexible piston rod 5 engage in a thread 8 of ratchet wheel 7having teeth 9 along the periphery thereof. An electrical motor 10electrically connected to a battery 11 and control means 12 is providedwith a gear 13 meshing with a gear 14 attached to an outwardly threadedspindle or shaft 15 received in an inwardly threaded nut 16 attached aplate 17 provided with two slits 18 and 19, extending parallel to theaxis of said spindle 15 and a third slit 20, extending at an angle tosaid axis. Two fixedly arranged pins 21 and 22 are received in the slits18 and 19, respectively such that the pins serve as guides to the to andfro displacement of the plate 17 by means of the spindle 15 when theelectrical motor 10 rotates first in one directional rotation andthereafter in the opposite directional rotation.

A protuberance 23 is arranged on the plate 17 to co-operate with two endstop contacts 24 and 25 electrically connected to the control means 12for reversing the direction of rotation of the electrical motor when theprotuberance 23 contacts one of the end stop contacts 24 or 25. A pawl26 is attached to a pivotable elongated body 27 having a pin 28 forbeing received in the oblique slit 20 and a hole 29 for receiving thepin 21 such that the body 27 is pivotable around the pin 21. A ratchet30 is fixedly attached to the housing 2 by means of a pin 31 and islocated so as to engage the teeth 9 of the ratchet wheel 7. The pawl 26is displaceable from a retracted position where it does not engage theteeth 9 of the ratchet wheel 7 and in an engaged position in which itengages the teeth of the ratchet wheel and rotates the ratchet wheel ina clockwise direction.

The displacement of the pawl 26 between the two positions indicatedabove takes place by the linear displacement of the plate 17. When theplate 17 is displaced in the direction from the end stop contact 24 tothe end stop contact 25, the oblique slit 20 urges the pin 28 of theelongated body 27 in a direction away from the carpule 3 such that theelongated body 27 pivots around the pin 21 in a clockwise direction,whereby the pawl 26 is moved in towards its retracted position relativeto the ratchet wheel 7. When the protuberance 23 on the plate 17contacts the end stop contact 25, the directional rotation of the motor10 is reversed and the plate 17 is displaced in the direction from theend stop contact 25 towards the end stop contact 24, whereby the obliqueslit 20 forces the pin 28 towards the carpule 3, whereby the elongatedbody 27 is forced to rotate in a counterclockwise direction whereby thepawl 26 is brought into contact with one of the teeth 9 of the ratchetwheel and rotates the ratchet wheel in a clockwise direction, while theratchet rides over one of the other teeth 9 for locking the ratchetwheel against rotation in the counterclockwise direction.

Thus, during one cycle of rotation in one direction and the oppositedirection of the electrical motor 10, the ratchet wheel 7 will beadvanced by one tooth corresponding to one displacement of the pawl 26from the retracted position thereof to the engaged position thereof.

Referring now to FIGS. 6-9, in this embodiment a coil spring 40 isattached to a pin 41 fixedly attached to the housing 2 and a pin 42fixedly attached to the plate 17.

When the plate 17 is moved in the direction from end contact 24 towardsthe end contact 25, the spring 40 is in tension, and when the plate 17moves back in a direction from the end stop contact 25 towards the endstop contact 24 after reversion of the direction of rotation of themotor 10, the spring 40 will be relaxed and exert a force in the samedirection as the motor 10 on the plate 17 and thus reinforcing the forceavailable to rotate the ratchet wheel 7.

Referring now to FIGS. 10-15, the electrical motor 10 is electricallyconnected to a battery and control means and the axle of the motor isconnected to a pair of twisted strings 35 or a band or similar device,which reduces its length when twisted and increases its length whenuntwisted, said length variation being provided by the rotation of themotor, i.e. the device is connected to the rotating axle of the motor atone end and connected to a pivotable body 78 at the opposite end. Thepivotable body is provided with an extension 78 a comprising a pawl 74arranged to engage the teeth 9 on the ratchet wheel 7, as indicated inFIGS. 15 a, 15 b, 15 c, whereby the pivoting of the pivotable body 78provides a rotation of the ratchet wheel 7. A second pawl mechanism 72,84 is provided to prevent rotation of the ratchet wheel 7 in theopposite direction, again as shown in FIGS. 15 a-15 c.

The displacement of the pawl 74 between the two positions indicated inFIGS. 15 a and 15 b is provided by the reduction of the length of thetwisted strings 35 by rotation of the motor and the displacement in theopposite direction is provided by the spring 40 during extension of thetwisted strings 35 provided by rotation of the motor in the oppositedirection, whereafter further rotation in this direction again reducesthe length of the twisted strings 35, whereby a complete cycle ofrotation in one direction of the motor provides a movement of thepivotable body from the position shown in FIG. 15 a to the positionshown in FIG. 15 b and back to the position shown in FIG. 15 a, thismovement being provided by the twisted strings 35 being untwisted andtwisted in the opposite direction during rotation of the motor in onedirection. Thus, the rotation of the motor in one direction of rotationprovides a full stroke for the pivotable body and thus the pawlmechanism moving the ratchet wheel one step forward and the followingrotation of the motor in an opposite direction of rotation provides afurther full stroke of the pivotable body and the pawl mechanism.

Thus, during one cycle of rotation in one direction and the oppositedirection of the electrical motor 10, the ratchet wheel 7 will beadvanced by two teeth corresponding to two displacements of the pawl 74.The pivotable body 78 comprises a protuberance 78 a which co-operateswith two end stop contacts 85 a and 85 b electrically connected to thecontrol means for controlling the reversal of the direction of rotationof the electrical motor when the protuberance 78 a contacts the end stopcontact 85 a. Due to the fact that the twisted strings 35 can onlyprovide a pulling force on the pivotable body 78, a spring 40 isconnected to the pivotable body to provide the movement in the directionshown by the arrow in FIG. 10.

In the embodiment shown in the figures spring 40 is a coil spring,however, other types of springs, such as a rod spring could be providedfor this purpose.

Referring now to FIG. 16, an actuator according to the invention isreferred to generally by the numeral 50 and is identical to the actuatorshown in FIGS. 10-14. This actuator may be employed for any userequiring transformation of a rotation to a linear movement or arotational force to a linear force.

A rotation motor 51 is attached to a pair of elongate, flexible elementssuch as strings or filaments 52 by means of a rotational body 53 thatmay or may not function as a fly wheel. The elements 52 are attached toa pin 54 on a pivotable plate. Rotation of the motor in the direction R1will twist the strings 52 such that the length thereof is shorteneduntil the pin 54 is displaced linearly in the direction R2 whereby theplate 55 is rotated around pivot 56 in the direction R3. A tensionspring 57 is attached to plate 55 at pin 58 and to a not shown frame atpin 59.

Rotation of the plate 55 will expand the spring 57 in the direction R4against the spring force thereof.

Rotation of the motor 51 in the direction opposite R1 will at firstuntwist the elements 52 whereby the length thereof becomes larger withthe consequence that the spring 57 rotates the plate 55 in the directionopposite R3.

Further rotation of the motor 51 in the; direction opposite R1 willtwist the elements 52 again an eventually exert a force on said pin 54in direction R2 again, the direction of rotation being subsequentlyreversed again and the cycle starts anew.

In case, a smaller interval is desired between each turn of the plate 55in the direction R3, the motor 51 may reverse direction of rotation assoon the elements 52 have become untwisted to an extent that the spring57 has pivoted the plate a certain distance in the direction oppositeR3.

Reference is now made to FIGS. 17 a-17 b, where a motor 51 is attachedto both opposed ends of an elongate, flexible element such as a stringor filament 52 by means of a rotational body 53 that may or may notfunction as a fly wheel. The element 52 forms a loop 60 within which arelocated two bodies 61 and 62.

The body 61 is displaceable along a groove 63 in which a pin 64 of thebody is slideably received. A spring 65 is attached to the displaceablebody 61 such that displacement of said body 61 in the direction R5 takesplace against the biasing force exerted by the spring 65.

The other body 62 is fixedly arranged such that when twisting of theelement 52 by rotation of the motor 51 takes place the loop 60 isreduced in size as seen in FIG. 17 b and the displaceable body 61 isforced towards the fixed body 62 along the groove 63 and against thespring force of the spring 65.

When the rotational direction of the motor is reversed so that itrotates in the direction R7, the element 52 will be untwisted, the loop60 will enlarge and the spring 65 will displace the body in thedirection R6.

Although the groove is shown extending substantially linearly, it mayobviously be curved and extend at different angles to the axis of themotor.

The body 61 may be attached to a multitude of different driving ortransmission mechanisms, for example the ratchet and pawl mechanismsshown in FIGS. 1-9.

A displaceable body should be taken to mean any body that can changeposition either by linear motion, curved motion, rotative motion, etc.and any combination thereof under the influence of a force applied to apoint on or in said body.

Displacement should likewise be taken to mean any change in positionresulting from linear motion, curved motion, rotative motion, etc. andany combination thereof.

1. A wearable medicine dispenser device, comprising: a piston rod toforce medicine from the device; a drive mechanism to advance the pistonrod, the drive mechanism comprising a pawl and a driven member, the pawlpositioned to engage one or more teeth of the driven member, wherein thepawl is adjustable between a first position and a second position toincrementally advance the driven member; and a rotational motor coupledto the pawl so that the pawl is at least partially adjusted toward oneof the first position or the second position in response to one or morefull rotations of the rotational motor.
 2. The wearable medicinedispenser device of claim 1, further comprising an elongate stringmember coupled to the pawl and coupled to the rotational motor.
 3. Thewearable medicine dispenser device of claim 2, wherein one or more fullrotations of the rotational motor causes the string member to act uponthe pawl.
 4. The wearable medicine dispenser device of claim 2, whereinthe pawl comprises a pivotable body.
 5. The wearable medicine dispenserdevice of claim 2, wherein the elongate string member comprises aflexible element selected from the group consisting of: a string, afilament, a strip, and a ribbon.
 6. The wearable medicine dispenserdevice of claim 1, further comprising a bias member coupled to the pawlto urge the pawl toward the second position and incrementally advancethe driven member.
 7. The wearable medicine dispenser device of claim 6,wherein the rotational motor pivots the pawl toward the first positionin response to one or more full rotations of the rotational motor. 8.The wearable medicine dispenser device of claim 1, further comprising ahousing that defines a cavity to receive a medicine container.
 9. Thewearable medicine dispenser device of claim 8, wherein the piston rod isadvanced toward the medicine container when the medicine container isreceived in the cavity.
 10. The wearable medicine dispenser device ofclaim 1, further comprising a control circuit device to repeatedlyreverse the direction of rotation of the rotational motor.
 11. Thewearable medicine dispenser device of claim 1, wherein the driven memberis a ratchet wheel.
 12. The wearable medicine dispenser device of claim11, wherein the pawl is adjustable to the first position in which thepawl is retracted away from one or more teeth of the ratchet wheel. 13.The wearable medicine dispenser device of claim 1, further comprising alinearly displaceable plate coupled to the pawl and coupled to therotational motor.
 14. The wearable medicine dispenser device of claim13, wherein one or more full rotations of the rotational motor causesthe linearly displaceable plate to act upon the pawl.
 15. A wearablemedicine dispenser device, comprising: a piston rod to force medicinefrom the device; a drive mechanism to advance the piston rod; anelongate string member coupled to the drive mechanism; and a rotationalmotor coupled to the string member so that one or more full rotations ofthe rotational motor causes the string member to adjust the drivemechanism to advance the piston rod.
 16. The wearable medicine dispenserdevice of claim 15, wherein the drive mechanism comprises a pawl and adriven member, the pawl positioned to engage one or more teeth of thedriven member to incrementally advance the driven member.
 17. Thewearable medicine dispenser device of claim 16, wherein the pawlcomprises a pivotable body that is connected with the elongate stringmember.
 18. The wearable medicine dispenser device of claim 17, whereinthe one or more full rotations of the rotational motor twists the stringmember and causes the string member to pull upon the pivotable body tothereby adjust the pawl relative to the driven member.
 19. The wearablemedicine dispenser device of claim 16, wherein the driven member is aratchet wheel.
 20. The wearable medicine dispenser device of claim 19,wherein the pawl is positioned to engage one or more teeth of theratchet wheel so as to incrementally rotate the ratchet wheel in adriving direction.
 21. The wearable medicine dispenser device of claim20, further comprising a second pawl positioned to engage the one ormore teeth of the ratchet wheel to inhibit rotation of the ratchet wheelopposite the driving direction.
 22. The wearable medicine dispenserdevice of claim 15, further comprising a housing that defines a cavityto receive a medicine container.
 23. The wearable medicine dispenserdevice of claim 22, wherein the piston rod is advanced toward themedicine container when the medicine container is received in thecavity.
 24. The wearable medicine dispenser device of claim 15, whereinthe elongate string member comprises a flexible element selected fromthe group consisting of: a string, a filament, a strip, and a ribbon.25. The wearable medicine dispenser device of claim 15, wherein thestring member comprises a loop such that the one or more full rotationsof the rotational motor twists the loop.
 26. The wearable medicinedispenser device of claim 15, further comprising a control circuitdevice to repeatedly reverse the direction of rotation of the rotationalmotor.
 27. A wearable medicine dispenser device, comprising: a housingthat defines a cavity to receive a medicine container; a piston rodmovable in a forward direction toward the medicine container when themedicine container is received in the cavity; a drive mechanism toadvance the piston rod in the forward direction, the drive mechanismcomprising a pawl and a ratchet wheel, the pawl positioned to engage oneor more teeth of the ratchet wheel, wherein the pawl is pivotablebetween a first position and a second position to incrementally advancethe ratchet wheel; a bias member coupled to the pawl to urge the pawltoward the second position to incrementally advance the ratchet wheel;an elongate string member coupled to the pawl; and a rotational motorcoupled to the string member so that one or more full rotations of therotational motor causes the string member to twist and thereby urge thepawl toward the first position.
 28. The wearable medicine dispenserdevice of claim 27, further comprising a second pawl positioned toengage the one or more teeth of the ratchet wheel to inhibit rotation ofthe ratchet wheel opposite the driving direction.
 29. The wearablemedicine dispenser device of claim 27, wherein the elongate stringmember comprises a flexible element selected from the group consistingof: a string, a filament, a strip, and a ribbon.
 30. The wearablemedicine dispenser device of claim 27, wherein the string membercomprises a loop such that the one or more full rotations of therotational motor twists the loop.
 31. The wearable medicine dispenserdevice of claim 27, further comprising a control circuit device torepeatedly reverse the direction of rotation of the rotational motor.32. A method of dispensing liquid medicine, comprising: in a dispensingcycle, rotating a motor one or more full revolutions in a firstrotational direction to twist or untwist a string member and therebyadjusting a ratchet mechanism coupled to a piston rod, wherein theadjustment of the ratchet mechanism incrementally advances the pistonrod in a forward direction to force medicine from a wearable medicinedispenser device; and in a next dispensing cycle, rotating the motor oneor more full revolutions in an opposite, second rotational direction totwist or untwist the string member and thereby adjusting the ratchetmechanism coupled to the piston rod, wherein the adjustment of theratchet mechanism incrementally advances the piston rod in the forwarddirection to force medicine from the wearable medicine dispenser device.33. The method of claim 32, wherein the ratchet mechanism comprises apawl and a driven member, the pawl being positioned to engage one ormore teeth of the driven member to incrementally advance the drivenmember.
 34. The method of claim 33, wherein the pawl comprises apivotable body that is connected with the string member, said rotatingof the motor twists the string member and causes the string member topull upon the pivotable body to thereby adjust the pawl relative to thedriven member.
 35. The method of claim 32, wherein the wearable medicinedispenser device comprises a housing that defines a cavity to receive amedicine container, the piston rod being advanced in the forwarddirection toward the medicine container when the medicine container isreceived in the cavity.